import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("title"),
        leading: Text("哈哈leading",style: TextStyle(color: Colors.yellow),),
        flexibleSpace: Container(width: double.infinity,height: 20,color: Colors.green,),
        elevation: 10,
        backgroundColor: Colors.pink,
        centerTitle: false,
      ),
      body: Center(
        child: Container(
          width: double.infinity,
          height: double.infinity,
          color: Colors.green,
        ),
      ),
      // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}
